fn prefix_len(s: &[u8]) -> (usize, usize)Expand description
Return the length of a prefix of S that corresponds to the suffix defined by this extended regular expression in the C locale: (.[A-Za-z~][A-Za-z0-9~])$ Use the longest suffix matching this regular expression, except do not use all of S as a suffix if S is nonempty. If *LEN is -1, S is a string; set *LEN to S’s length. Otherwise, *LEN should be nonnegative, S is a char array, and *LEN does not change.